Loft block with aligned sheaves

ABSTRACT

A lift system configured to lift an article (e.g., a batten). The lift system includes a first cable configured to be coupled to the article, a second cable configured to be coupled to the article, a drive mechanism coupled to the first cable and the second cable and operable to raise and lower the article, a first loft block including a first loft sheave to redirect the first cable from a first substantially horizontal axis to a first substantially vertical axis, and an idler sheave to direct the second cable along a second substantially horizontal axis. The lift system further includes a second loft block including a second loft sheave to redirect the second cable from the second substantially horizontal axis block to a second substantially vertical axis.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/552,290, filed Oct. 27, 2011, the entire contents of which arehereby incorporated by reference herein.

BACKGROUND

The present invention relates to theatre rigging equipment andspecifically to lift systems for raising and lowering a load intheatrical and staging environments.

Performance venues such as theaters, arenas, concert halls, auditoriums,schools, clubs, convention centers, and television studios can employbattens or trusses to suspend, elevate, and/or lower lighting, scenery,draperies, and other equipment that can be moved relative to a stage orfloor. Such battens can include pipe or joined pipe sections that form adesired length of the batten. Battens can be 50 feet or more in length.To support heavy loads or suspension points are that spaced apart (e.g.,15-30 feet apart), the battens may be fabricated in variousconfigurations, such as ladder, triangular, or box truss configurations.A number of elevating or hoisting or lift systems are available forsupporting, raising, and lowering battens and/or articles used in suchvenues.

One such lift system utilizes elongated flexible members, such ascables, to provide movement to the batten. Loft blocks. are commonlymounted above the stage to facilitate directing the cables from ahorizontal orientation to a vertical orientation. Lift systems of thistype are disclosed in U.S. Pat. No. 8,033,528; U.S. Pat. No. 7,775,506;U.S. Patent Application Publication No. 2009/0127527, and InternationalPatent Application Publication No. WO 2011/063141. The entire contentsof each of the above-reference patent applications is herebyincorporated by reference herein in their entirety.

SUMMARY

In one embodiment, the invention provides a lift system configured tolift an article (e.g., a batten). The lift system includes a first cableconfigured to be coupled to the article, a second cable configured to becoupled to the article, a drive mechanism coupled to the first cable andthe second cable and operable to raise and lower the article, a firstloft block including a first loft sheave to redirect the first cablefrom a first substantially horizontal axis to a first substantiallyvertical axis, and an idler sheave to direct the second cable along asecond substantially horizontal axis. The lift system further includes asecond loft block including a second loft sheave to redirect the secondcable from the second substantially horizontal axis block to a secondsubstantially vertical axis.

In another embodiment, the invention provides a loft block assemblyincluding a hanger configured to be secured to a structural member, aloft sheave coupled to the hanger and configured to direct a first cablefrom a first orientation to a second orientation, the loft sheavemounted for rotation about a loft axis and within a loft planeperpendicular to the loft axis. The loft block assembly further includesan idler coupled to the hanger and configured to guide a second cablethrough the loft block assembly, the idler mounted within the loftplane.

In another embodiment, the invention provides a loft block assemblyincluding a hanger configured to be secured to a structural member, aloft sheave coupled to the hanger and configured to redirect a firstcable from a first substantially horizontal axis to a substantiallyvertical axis, and an idler coupled to the hanger for movement with thehanger and configured to direct a second cable along a secondsubstantially horizontal axis. The idler is located at least partiallyabove the first horizontal axis and the substantially vertical axisextends through the idler such that at least a portion of the idlervertically overlaps the loft sheave.

Other aspects of the invention will become apparent by consideration ofthe detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a lift system according to an embodimentof the invention.

FIG. 2 is a left front perspective view of a loft block assembly of thelift assembly of FIG. 1.

FIG. 3 is right front perspective view of the loft block assembly ofFIG. 2.

FIG. 4 is a rear perspective view of the loft block assembly of FIG. 2.

FIG. 5 is a section view taken along line 5-5 in FIG. 7.

FIG. 6 is a front view of the loft block assembly of FIG. 2.

FIG. 7 is a top view of the loft block assembly of FIG. 2.

FIG. 8 is a bottom view of the loft block assembly of FIG. 2.

FIG. 9 is a side section view taken along line 9-9 in FIG. 7.

DETAILED DESCRIPTION

FIG. 1 illustrates a lift system 10 that is operable to raise and loweran article, which includes a batten B in the illustrated embodiment. Thelift system 10 includes a drive mechanism 11. The illustrated drivemechanism 11 includes a motor 12, for example, an electric motor, agearbox 13, a traction drive 14, and a drum 15. The motor 12 is operableto rotate the drum 15, via the gearbox 13, in a winding (raising)rotation and an unwinding (lowering) rotation of the drum 15.

The lift system 10 further includes a plurality of cables 16. The cables16 can be wound and unwound about the drum 15 via operation of the motor12, which rotates the drum 15, to raise and lower the batten B. Thecables 16 can include any suitable flexible member, including wire,rope, and the like. The illustrated cables 16 extend from the drivemechanism 11 in a generally horizontal orientation to a plurality ofloft block assemblies 20 that redirect the cables 16 to a generallyvertical orientation. In the illustrated embodiment, each of the loftblock assemblies 20 are generally the same so only one of the loft blockassemblies 20 will be described in detail.

Referring to FIG. 2, the loft block assembly 20 is adapted to be securedto a structural member, such as an I-beam truss 22 in a building. Forexample, the loft block assembly 20 can be secured to the lower edge ofthe ceiling truss 22. It should be understood that the loft blockassembly 20 can be modified to be secured to other structural membershaving other shapes.

The illustrated loft block assembly 20 includes a hangar 24 having twoparallel side walls 26 connected to each other by a top wall 28. In theillustrated embodiment, the top wall 28 and the side walls 26 areintegrally formed as a single component, and in other embodiments, thewalls 26 and 28 can be made as separate components and fastenedtogether. A series of three spacers 30 maintain a desired spacingbetween the side walls 26, and three corresponding fasteners 32 securethe spacers to the side walls 26. A loft sheave 34 is mounted forrotation between the side walls 26 and is held in position by a sheaveaxle 36. Similarly, an idler member in the form of an idler sheave 38 ispositioned between the side walls 26 and is mounted for rotation aboutan idler axle 40 parallel to the sheave axle 36. A first cable 16A isdesigned to travel along a substantially horizontal axis H that extendsthrough the center of cable 16A as illustrated in FIG. 2, wrap around aportion of the loft sheave 34, and continue travel along a substantiallyvertical axis V that extends through the center of cable 16A asillustrated in FIG. 2 until the end of the first cable 16A is attachedto the batten B (in any suitable manner). Referring to FIG. 5, two ofthe spacers 30 are positioned closely adjacent to the loft sheave 34 inorder to keep the first cable 16A in a groove 37 of the loft sheave 34.Other cables 16B, 16C, 16D pass above the forward-most spacer 30 andonto the idler sheave 38 to pass through the loft block assembly 20 andonto the other loft blocks assemblies 20 (see FIGS. 1, 5, and 6).

With continued reference to FIG. 2, a top end portion 39 of the hangar24 includes a support 41 that attaches the loft block assembly 20 to thestructural member 22. The illustrated support 41 includes a stationaryhook support 42 secured to the side walls 26 by two bolts 44 on eachside. A flange plate 46 is wrapped around the outer surfaces of the sidewalls 26 and is secured in place by two of the bolts 44 used to securethe stationary hook support 42. The flange plate 46 includes astationary sloped surface 47 that is adapted to engage a lower edge ofthe ceiling truss 22. The flange plate 46 is positioned in the oppositeside of the I-beam truss 22 from where the cables 16 are powered, andthus the flange plate 46 acts as a structural member to take a largepart of the angular load applied to the loft block assembly 20 by thehorizontal and vertical legs of the cables 16.

A moveable hook support 48 is positioned between the side walls 26 formovement toward and away from the stationary hook support 42. Themoveable hook support 48 includes a sloped surface 50 that is adapted toengage the lower edge of the ceiling truss 22. The moveable hook support48 is moved relative to the stationary hook support 42 by a tension bolt52. The tension bolt 52 is inserted through a washer 54 and the moveablehook support 48 and is threaded into a threaded insert 56 (FIGS. 5 and8) on the stationary hook support 42. By virtue of this arrangement,rotation of the tension bolt 52 results in movement of the movable hooksupport 48 relative to the stationary hook support 42 to clamp the loftblock assembly 20 to the truss 22.

The loft block assembly 20 further includes a suspender 60 that issandwiched between one of the spacers 30 and the side walls 26 of thehanger 24. The suspender 60 has an inverted V-shape and is positionedsuch that the upper portion of the inverted V wraps around the uppersurface of the tension bolt 52, as best shown in FIG. 5. The purpose ofthe suspender 60 is to inhibit downward rotation of the hanger 24relative to the I-beam truss 22 as force is applied to the cables 16.

Referring to FIGS. 6 and 7, it can be seen that both the idler sheave 38and the loft sheave 34 are centered between the side walls 26 of thehangar 24. In this regard, a vertical plane 64 perpendicular to thesheave axle 36 and centered on the loft sheave 34, as illustrated inFIG. 6, will pass through the center of the idler sheave 38 andperpendicular to the idler axle 40. Referring to FIG. 7, it can be seenthat the idler sheave 38 and loft sheave 34 are also aligned with thebatten B. In addition, referring to FIG. 9, it can be seen that aportion of the idler sheave 38 vertically overlaps with the loft sheave34 by a horizontal distance D, and thus is positioned vertically above aportion of the loft sleave 34. Alternatively stated, as shown in FIG. 9,a portion of the idler sheave 38 is located above the horizontal axis Hof the cable 16A and the vertical axis V of the cable 16A extendsthrough the idler sheave 38 because the idler sheave 38 is positioned inthe plane 64 (FIG. 6). In the illustrated embodiment, the horizontalaxis H of the cable 16A extends through the idler axel 40 such thatabout half of the idler sheave 38 is positioned above the horizontalaxis H. In other embodiments, more or less than half of the idler sheave38 can be positioned above the horizontal axis H.

Thus, the illustrated device provides, among other things, a loft blockassembly that can be easily secured to an overhead truss. In additionthe illustrated device improves the compactness of the design and alignsthe forces on the loft block assembly by aligning the loft sheave withthe idler sheave. Various features and advantages of the invention areset forth in the following claims.

1. A lift system configured to lift an article, the lift systemcomprising: a first cable configured to be coupled to the article; asecond cable configured to be coupled to the article; a drive mechanismcoupled to the first cable and the second cable and operable to raiseand lower the article; a first loft block including a first loft sheaveto redirect the first cable from a first substantially horizontal axisto a first substantially vertical axis, and an idler sheave to directthe second cable along a second substantially horizontal axis; and asecond loft block including a second loft sheave to redirect the secondcable from the second substantially horizontal axis to a secondsubstantially vertical axis.
 2. The lift system of claim 1, wherein theidler sheave of the first loft block is located at least partially abovethe first horizontal axis.
 3. The lift system of claim 2, wherein thefirst vertical axis extends through the idler sheave such that at leasta portion of the idler sheave vertically overlaps with the first loftsheave.
 4. The lift system of claim 3, wherein the first loft blockincludes a support adjacent a top end of the first loft block andconfigured to attach the first loft block to a structural member,wherein the idler sheave is located at least partially above the firsthorizontal axis such that at least a portion of the idler sheave islocated between the first horizontal axis and the support in a directionalong the first vertical axis.
 5. The lift system of claim 1, whereinthe first loft sheave is mounted for rotation about a loft axis andwithin a loft plane perpendicular to the loft axis, and wherein theidler sheave is mounted within the loft plane.
 6. The lift system ofclaim 5, wherein the idler sheave is centered on the loft plane.
 7. Thelift system of claim 5, wherein the idler sheave is mounted for rotationin the loft plane.
 8. The lift system of claim 7, wherein the idlersheave is mounted for rotation about an idler axis, and wherein theidler axis is parallel to the loft axis.
 9. The lift system of claim 5,wherein the idler sheave is centered on the loft plane.
 10. A loft blockassembly comprising: a hanger configured to be secured to a structuralmember; a loft sheave coupled to the hanger and configured to direct afirst cable from a first orientation to a second orientation, the loftsheave mounted for rotation about a loft axis and within a loft planeperpendicular to the loft axis; and an idler coupled to the hanger andconfigured to guide a second cable through the loft block assembly, theidler mounted within the loft plane.
 11. The loft block assembly ofclaim 10, wherein the idler is centered on the loft plane.
 12. The loftblock assembly of claim 10, wherein the idler comprises an idler sheavemounted for rotation about an idler axis.
 13. The loft block assembly ofclaim 12, wherein the idler sheave is mounted for rotation in the loftplane.
 14. The loft block assembly of claim 13, wherein the idler sheaveis centered on the loft plane.
 15. The loft block assembly of claim 10,wherein at least a portion of the idler is positioned directly above atleast a portion of the loft sheave.
 16. A loft block assemblycomprising: a hanger configured to be secured to a structural member; aloft sheave coupled to the hanger and configured to redirect a firstcable from a first substantially horizontal axis to a substantiallyvertical axis; and an idler coupled to the hanger and configured todirect a second cable along a second substantially horizontal axis,wherein the idler is located at least partially above the firsthorizontal axis and the substantially vertical axis extends through theidler such that at least a portion of the idler vertically overlaps theloft sheave.
 17. The loft block assembly of claim 16, the loft blockfurther comprising a support adjacent a top end of the loft blockconfigured to attach the loft block to the structural member, whereinthe idler is located at least partially above the first horizontal axissuch that at least a portion of the idler is located between the firsthorizontal axis and the support in a direction along the vertical axis.18. The loft block assembly of claim 16, wherein the loft sheave ismounted for rotation about a loft axis and within a loft planeperpendicular to the loft axis, and wherein the idler is coupled to thehanger such that the idler is mounted within the loft plane.
 19. Theloft block assembly of claim 18, wherein the idler is centered on theloft plane.
 20. The loft block assembly of claim 18, wherein the idleris mounted for rotation in the loft plane.
 21. The loft block assemblyof claim 18, wherein the idler is mounted for rotation about an idleraxis, and wherein the idler axis is parallel to the loft axis.